Synchronous optical networks (SONET) have been around for many years. In recent years methods for designing both unidirectional path switch ring (UPSR) and bilateral switch ring (BLSR) type SONET networks have been developed, and some of these methods have been implemented using software tools for mechanizing designs. With the development of Next Generation SONET (NGSONET), new features and capabilities have been added to SONET add-drop multiplexers (ADMs). Sub-tending rings are one of these new features. A typical SONET network in a major metro area can have hundreds of UPSR elements and different ring speeds. High-speed rings, traditionally designated as OC192 rings, can also have a sub-tending ring attached to the rings. The “Sub-tending Ring” feature allows a higher bit rate ring to act as a node on a lower bit rate ring. Thus, the same ADM can function as a node on multiple rings with different bit rates. For example a node on an OC192 ring can also have a sub-tending OC48 ring attached to it. The design of sub-tending rings on a parent ring is a new challenge and conventional systems do not adequately provide a systematic design of sub-tending rings in a metro network environment.
Accordingly, there is a need for an improved method and system of developing SONET ring networks with sub-tending rings.